The year 2005 marks the first direct detection of the light radiated
by an extrasolar planet [1]}, [2]}. The observations
were made by the Spitzer space telescope [3]} at \(4.5\) , 8
and 24 \(\mu m\) , not easily accessible by ground-based instruments.
Although it was quite expectable that a similar measurement in the near
infrared could also be possible by ground-based \(4~m\) -class telescopes,
two years passed until the first tentative observation of that kind
[4]}. Since then, secondary eclipse (occultation)
observations at the \(2.2\)  \(\mu m\)  (2MASS K – or Ks) band still remained
in the realm of ground-based instruments, due to the lack of space
instruments at this wavelength [5]}, [6]}, [7]}.
The 2MASS bands are especially suitable for the observation of hot
extrasolar planets, due to the expected peaking of the black-body flux
in \(\sim 1-2\)  \(\mu m\)  for temperatures between 1500 and 2000 K, i.e.,
for the characteristic equilibrium temperatures of extrasolar planets
[8]}.
